I recall an Asimov short story from the 1950s or before, in which a reporter character hides a mini-typewriter in a pocket, so he can surreptitiously type notes during an interview. It's a great example of a bad prediction of new technology, since Asimov didn't postulate a miniature wire or tape recorder, even though both of those technologies existed when he wrote the story - but I don't remember what story it was.
This sounds like the framing story for I, robot. The reporter interviewing Susan Calvin has a device in his pocket to record the interviews:
I was taking it down verbatim on my pocket-recorder, trying not to show the knuckle-motions of my hand. If you practice a bit, you can get to the point where you can record accurately without taking the little gadget out of your pocket.