You can use the Apple Pencil (1st generation) with these iPad models:
iPad mini (5th generation) iPad (6th, 7th, 8th and 9th generation) iPad (10th generation)* iPad Air (3rd generation) iPad Pro (12.9", 1st and 2nd generation) iPad Pro (10.5") iPad Pro (9.7")
* To pair and charge the Apple Pencil with an iPad (10th generation), the USB-C to Apple Pencil adapter is required.