Starting with iPadOS 13.4, Apple provided the ability to use a Bluetooth mouse or trackpad with an iPad, a very handy feature for those who want to use the tablet as a laptop alternative or replacement. To connect one of the accessories:
° Turn on your Bluetooth accessory and place it near your iPad.
° Make sure that your accessory is in pairing or discovery mode. An Apple Magic Mouse and Magic Trackpad should be ready to pair at this point. If you’re pairing a third-party accessory that you’ve used with another device, follow the pairing-mode steps from its manufacturer.
° Open the Settings app on your iPad.
° Tap Bluetooth.
° Look under Other Devices for your Bluetooth accessory, then tap its name to pair it with your iPad.
Depending on the accessory that you’re connecting, you might need to take extra steps. Follow any onscreen instructions that appear. If you’re pairing with Apple Magic Mouse or Magic Trackpad and you’re asked to provide a code, use 0000 (four zeros).
If you’re having trouble connecting your accessory, try these tips from Apple.
(This how-to is based on my experiences and info on Apple’s support pages — where the images sometimes come from.)