pick someone's brain
idiom

- to get information and advice from someone

(Cambridge Dictionary of American Idioms)

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To pick someone's brain uses pick in the sense of harvesting or gathering something like crops. In this case, it is information that is being picked. To avoid being accused of stealing information however, it's best to ask someone if you can pick their brain.

As Robert Frost once said, the brain is a wonderful organ - it starts working the moment you get up in the morning and does not stop until you get into the office. It's also a versatile word as seen by these other idioms:

- an idle brain is the devil's workshop = People who have nothing worthwhile to think about will usually think of something bad to do (I give my son various tasks because an idle brain is the devil's workshop).

- rack one's brain = to try very hard to think of something (I racked my brain the entire morning to come up with a solution)

- have one's brain on a leash = to be drunk (Don't serve him any more alcohol because he already has his brain on a leash)

Note: Although we only have one of them, brain is often used in the plural with expressions and idioms (I racked my brains, I picked his brains, etc...)

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PRACTICE OWAD TODAY

Say something like:
"Instead of Googling for information, be social and PICK SOMEONE'S BRAIN. It can be a lot more interesting."