Smith, Jane. Personal interview. 19 May 2014.
or if you have more details...
Smith, Jane. Conducted by Terry Gross. Fresh Air, National Public Radio, WTTM, 20 Apr. 2022.
From the Purdue OWL:
"Personal interviews refer to those interviews that you conduct yourself. List the interview by the name of the interviewee. Include the descriptor Personal interview and the date of the interview."
If you're looking for an expert source:
You might also be able to use someone who has personal experience relating to your topic:
The Librarians may be able to help with ideas for interviewees. Use Ask a Librarian, to contact the librarians or email Lisa (firstname.lastname@example.org) directly, to get help from a librarian without coming up to the library.
Depending on your topic, you might even be able to interview a librarian with expertise or experience in certain fields!
If you are looking for a written interview with a well-known person, simply search for the person's name along with the word interview.
For example in MegaSearch or Proquest: Ryan Reynolds Interview