The meaning of "pick one’s brain" is:
The definition of "pick one’s brain" is:
(verb) to get information about something by asking someone who is an expert or who has a lot of information
I often pick Steve’s brain about repairing my car, because he’s a mechanic.
A: Hi there, are you a doctor?
Doctor: Why, yes I am!
A: Would you mind if I picked your brain for a moment?
Doctor: Not at all. What would you like to know?
A: Do you think my arm is broken?
The famous chef was angry, because people were always picking his brain for cooking tips.