Every once in a while, we may send an update to the firmware that runs on Pencil. This is code that runs on Pencil that may enable new capabilities or improve performance. You should try to keep current with the latest updates. You can see a list of all firmware versions and instructions for checking your firmware version here.
While you can check your firmware version and battery status in Paper 4, it's not possible to update your firmware. This functionality will be returning to Paper in a future update.