Kevin King, Attorney at <a href="HTTP://ESSENTIALAW.COM">ESSENTIAL LAW SERVICES</a>. The information presented here is general in nature and is not intended and should not be construed as legal advice for a particular case. This post does not create any attorney-client relationship with the author of the question answered. For specific advice about your particular situation, consult with me or other qualified legal counsel.
Assuming you are asking whether such conduct is unlawful, the answer is yes. It is a violation of California Penal Code section 632 to record someone's voice when they are unaware of the recording. It is not only a misdemeanor, but violation of the Code allows the victim to seek a civil penalty of $5,000 for each recording made in violation of the Code.
If you are a woman, depending on other factors, this may also be a violation of the criminal law related to taking pictures by hidden camera in an attempt to capture pictures up a woman's skirt, which can carry far greater criminal penalties.
Good luck to you.
This answer should not be construed to create any attorney-client relationship. Such a relationship can be formed only through the mutual execution of an attorney-client agreement. The answer given is based on the extremely limited facts provided and the proper course of action might change significantly with the introduction of other facts. All who read this answer should not rely on the answer to govern their conduct. Please seek the advice of competent counsel after disclosing all facts to that attorney. This answer is intended for California residents only. The answering party is only licensed to practice in the State of California.