Yes he did.
From Quora:
"He’ll usually use just a typical Fender (the 351 style) heavy pick. As a Beatle, he’d use a heavier felt pick as well as a Bert Weedon brand “home base” shaped pick.
As for strings, he was using Pyramid flat wound (they’re the original manufacturer for Hofner strings). He then went to Rotosound with their flats by the mid-‘60s, then went to Rotosound Tru Bass nylon black strings during the Let it Be sessions.
By the time of the late 80s and early 90s, he went back to the Rotosound flats. By the late 90s and into the early 2000s, he was using LaBella flats. Then as of 2010, he’s gone back to using Pyramid flats.
*once in a blue moon, he did use round wound strings, but never for a long amount of time as opposed to him using flats. This was told to me by Will Lee when he was actually holding Paul’s Hofner."