I imagine if someone leaked it they probably wouldn’t immediately admit to it just when asked.
"At the conclusion of the initial interviews, each employee was asked to sign an affidavit, under penalty of perjury, affirming that he or she did not disclose the Dobbs draft opinion to any person not employed by the Supreme Court, did not disclose to any person not employed by the Supreme Court any information relating to the Dobbs draft opinion not made public through means authorized by the Court, and had provided all of the pertinent information known to him or her relating to the disclosure or publication of the Dobbs draft opinion. Each employee was then asked to swear to the truth of the statements in the affidavit before a Notary Public. Each of these employees signed a sworn affidavit. A few of those interviewed admitted to telling their spouses about the draft opinion or vote count, so they annotated their affidavits to that effect. If investigators later determine any personnel lied to the investigators, those personnel would be subject to prosecution for a false statement in violation of 18 USC § 1001."
All the other references that I can find look like they are limited to the Court's IT systems. That seems like it might yield evidence that someone contacted the press (if they were careless enough to use their personal device), but little else.