A federal judge in Chicago ordered the world's largest retailer yesterday to pay a young inventor all of the profits it made on his invention.

Sears, Roebuck & Co. will have to pay about $60 million to Peter M. Roberts, his atorney said.

"It shows how a small man can receive justice even against an enormous corporation if right is on his side," Roberts told reporters. "Right is the strongest weapon a person can have."

Roberts,34, operates a delicatessen in Chattanooga, Tenn. "I know now I can put out a 'gone fishin' sogn anytime I want," he said.

A Sears lawyer said the copany would appeal the order by U. S. District Court Judge George N. Leighton.

The invention is a socket wrench with a quick - release feature that allows users - mainly auto mechanics and do-it-yourselfs - to change sockets with one hand.

Roberts designed the wrench when he was an 18-year-old clerk in a Sears store in Gardner, Mass. He filled out a "suggestion" form and sent it and a prototype of the wrench to Sears headquarters in Chicago.

Behind the scenes, Sears did tests that showed the design to have enormous sales and profit potential.But it had only gloomy news for Roberts.

The invention really was not new, the company told him. It would be expensive to make and would sell only to the extent that Sears promoted it, the company claimed. Besides, it said, the device would qualify for a patent of only limited scope, if any.

Meanwhile, Roberts had applied for a patent. When his then-lawyer found out the patent was going to be issued, he gave the news to Sears months before he gave it to his own client.

The upshot was that in July 1965, Roberts, unaware of any possible misrepresentations, assigned his patent rights to Sears in exchange for a royalty of 2 cents per wrench - up to a maximum of $10,000.

Within days after the agreement was signed by Roberts, who had a high school education and no business experience, Sears started to make 44,000 quick-release socket wrenches a week. By 1975, it had sold more than 19 million. It had a near monopoly.

Roberts sought help from Chicago lawyer Louis G. Davidson, who filed a suit charging fraud, breach of a confidential relationship and negligent misrepresentation.

During the trial, economic expects testifying for Roberts estimated Sear's profits on the wrenches so have been $44 million during the 11 1/2-year period covered by the suit.

A U.S. District Court jury ruled for Roberts and, in April 1978, the 7th U.S. Circuit Court of Appeals affirmed.

The initial litigation brought Roberts$1 million, paid by Sears last October, when the Supreme Court preserved the appeals court decision. But he wanted that to be a mere downpayment to David by Goliath.

And so he asked Judge Leighton to restore his patent rights and to award him the profits Sears has made from the start - the $44 million plus an estimated $8 million a year since Dec. 31, 1976. By that time, Sears had sold 6 million more wrenches, for a total of 25 million.

Yesterday - five months after his intial target date - Leighton ruled for Roberts. By 4 p.m. on June 15, Sears must reassign both the American and Canadian patent rights. If it doesn't, federal magistrate will be empowered to make the reassignment in the firm's name, the judge said.

Furthermore Sears must tally all of its profits on the invention and appear before him to present its accounting at 10a.m. July 9.

After winning the $1 million, Roberts said he never would have sued if Sears "had been honest with me in the first place. They told me at the start that there wasn't much need for my wrench and it probably would not sell very well."

The attorney hired to represent Roberts in the 1960s, Charles Fay, was found by the lower cosurts to have told Sears that he believed the quick-release was patentable - and then to have been retained by Sears for some "routine matters."

"so he was working for them, too, and I did't even know it," Roberts said at yesterday's news conference.

Since getting the $1 million, he said, he has bought a mobile home, given his wife a Mercury compact car, paid for a cataract operation for his 76-year-old mother and tried to be unaffected by his new wealth. CAPTION: Picture, Inventor Roberts with his wrench: "Right is the strongest weapon . . ." AP