Pencil will not work after paring

You can look here: https://support.apple.com/en-gb/HT205236

Do you have a cover on the iPad or a screen protector? If you do, that may have an effect on the pencil. Do you have a nib on the tip of the pencil? If so, take that off and try again.

If none of that applies to you, try a forced restart.

• iPad models with Face ID: Press and quickly release the Volume Up button. Press and quickly release the Volume Down button. Then press and hold the Power button until the device restarts.
• iPad with Home button, iPhone 6s or earlier, and iPod touch (6th generation) or earlier: Press and hold both the Home and the Top (or Side) buttons until you see the Apple logo.

After I updated my iPad Air 3 to iOS 13.5, I had a heck of a time getting my pencil to work again. I just kept force restarting my iPad until it finally connected and worked.

Would you by chance have another device to test the Pencil with? My wife has a 6th generation iPad which which I was able to pair the Pencil to test to make sure that it wasn’t the Pencil itself.

Which Apple Pencil?

Are you using the latest Ipados software? If not try updating. If that’s not helpful then go to bluetooth settings and see if pencil is connected and check the pencil’s battery.

If it failed to work on three other devices, I would think that’s a pretty good guess at this point. Good luck with the next one.