Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Not at the same time I don't think. The Pencil requires you plug it into the Lightning port for 1-2 seconds to quickly pair to the iPad Pro. You can use the Pencil on as many iPad Pro's as you like but you need to do the pairing each time you swapped to a different iPad Pro.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.