A federal grand jury investigating allegations of drug use on Capitol Hill has heard testimony that Rep. Ronald V. Dellums (D-Calif.) and some members of his staff bought and used marijuana and cocaine.

Informed sources said last night that the allegations against the seven-term congressman were made to the grand jury by a former House doorkeeper who pleaded guilty two weeks ago in U.S. District Court here to misdemeanor drug possession charges. The former doorkeeper, Robert Yesh, has been cooperating with investigators, according to the sources. Yesh could not be reached for comment last night.

Dellums, 47, chairman of the House District Committee and a leading liberal voice in the House, also could not be reached for comment.

Meanwhile, CBS News reported last night that the House ethics committee, which also is investigating possible drug use on the Hill, has notified Dellums that the committee is looking into allegations that he and his staff bought and used cocaine and marijuana. The Washington Post was unable to confirm the CBS report.

A Dellums staff member in the congressman's Oakland office said in a telephone interview last night that "as far as I know, there has been no formal notification" from the House committee that Dellums or his staff members are being investigated. The staff member, H. Lee Halterman, said that he had talked with Dellums and Washington staff members yesterday and learned that Dellums had talked "informally" with Rep. Louis B. Stokes (D-Ohio), chairman of the House ethics committee.

Halterman said he did not know if the two congressmen had talked before or after the televised report. "There is allegedly this guy who had made allegations against Ron and his staff" to the House committee, Halterman said. "We don't know what the allegations are and we don't know the basis of the allegations, so we have no comment based on that fact." Other Dellums staff members could not be reached last night.

Stokes and three other members of the committee--Rep. Hank Brown (R-Colo.), Vic Fazio (D-Calif.) and William Coyne (D-Pa.)--all declined comment last night when contacted by Post reporters.

Dellums is the third congressman whose name has been mentioned since the Justice Department and the House ethics committee began their investigations last July.

Federal investigators have also heard allegations of drug use by Rep. Charles Wilson (D-Tex.) and then-Rep. Barry Goldwater Jr.(R-Calif.), according to sources familiar with that investigation. Both men have denied any wrongdoing.

None of the three congressmen has been charged with any offense.

Two Washington men whose arrests last April prompted the federal and congressional investigations were indicted last November on charges of operating a cocaine distribution ring on Capitol Hill. Both were recently apprehended in Australia and federal authorities are working with officials there to return them to the United States.

After the two official probes began, the U.S. attorney's office here, at the request of top Justice officials, decided to break a longstanding policy of not investigating individual drug users and agreed to pursue the allegations of congressional drug use. A special task force of investigators from the U.S. Drug Enforcement Administration, the D.C. police and Capitol Hill police are involved in the investigations.

Dellums has represented California's Eighth District, which includes Oakland and Berkeley, since 1971.

In 1979, he was named chairman of the House District of Columbia Committee, on which he has been a strong advocate of home rule for the city.

At the 1980 Democratic convention, Dellums had his name placed in nomination for the presidency so he could speak against the MX missile, the draft and economic policies that hurt the poor. After the speech, he immediately withdrew.