House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass) yesterday voiced an extraordinary personal attack on freshman Republican Rep. Bruce Caputo of New York, saying he was trying to use the Korean influence-buying investigation "to propel himself into higher public life".

O'Neill said he had been told, in what he admitted was hearsay, that Caputo, junior gadfly on the House committee investigating the Korean affair, has two employees on his payroll checking on members' sex lives.

O'Neill renewed his charge that it was Caputo who leaked scret testimony - which O'Neill disouted - that Tongsun Park, central influence buying in Congress, had used O'Neill's office as a "hangout".

Caputo issued a statement expressing regret that O'Neill had made "defamatory statements which he himself describes as hearsay. I have, of course, never asked anyone on staff to collect such information. I challenge Mr. O'Neill to indentify the staff members he has accused and to produce evidence of these charges!"

O'Neill who has been angered by attempts to link him with Tongsun Park and has a habit of talking candidly and emotionally when some politicians would remain silent, was interviewed by columinists Rowland Evans and Robert Novak for their syndicated television program. When the interviewer mentioned Caputo, O'Neill was off and running:

"Well, I don't have any confidence in him," said O'Neill of the most junior Republican and pushiest member of the House ethics committee conducting the Korean investigation. "From what I've been told he has two employes on his payroll who check the sex life of his colleagues, who check to see if they are out cheating on their wives, who check if they go on corporate planes.

"Now, if he feels he want to have his employes do that, and that's what I understand, does he have any respect for his fellow man? No. His fellow congressman? No. He leaked everything, from what I can gather, and he's exaggerated.

'He's trying to propel himself into higher public life. To me - unbelievable.It's a rare occasion a man the type of Caputo comes to the Congress of the United States, and I don't think it's good for Congress."

Asked if he was certain of what he said , O'Neill admitted it came to him secondhand but, "the people who told me this I trust."

O'Neill has been unhappy with Caputo throughout the Korean investigation. last fall the speaker took the House floor to denounce Caputo for releasinf-smear testimony about Tongsun Park using his majority leader office before he became Speaker. O'Neill said he had checked and found Park had been in th office no more than two or three times. "I never had half a dozen conversations with the man, said O'Neill yesterday. "I never talked about Korea with him."

O'Neill, through an aide, refused further comment.

The Speaker's staff members said he was relying on more than newspaper reports for his statements about Caputo. But they did refer reporters to a Washington Post article of last May 18, by staff writer Charles R. Babcock reporting that the ethics commmittee and adding that it was no secret to reporters covering the investigation that two of Caputo's staff members had been making their own inquires about the South Korean influence-buying charges.

The Post report also cited a United Press Internationl account which quoted an unnamed committee member, who The Post said was "generally recognized as Caputo," as saying that one of his staff members had visited the Rotunda restaurant on Capitol Hill to talk to its maitre d' two days before he was murdered. The unnamed member told UPI that his aide was "checking out rumors of wrongdoing , including by members of Congress, at the restaurant."