Use an Apple wireless keyboard, mouse, or trackpad
An Apple wireless keyboard, mouse, or trackpad uses Bluetooth to communicate with your Mac.
Make sure the device you’re setting up has charged batteries and is turned on. If the device has a built-in battery, use a Lightning to USB Cable to charge it with your Mac.
Choose Apple menu > System Preferences, then click Keyboard, Mouse, or Trackpad.
If you’re setting up a mouse or trackpad, follow the onscreen instructions. When your mouse or trackpad is discovered, it automatically connects with your Mac.
If you’re setting up a keyboard, click Set Up Bluetooth Keyboard, then follow the onscreen instructions to connect with your keyboard.
Keep these things in mind when using an Apple Bluetooth device:
If your Bluetooth device uses AA batteries, you receive a warning when the batteries are running low, but it’s a good idea to have a spare set of batteries available.
If you won’t be using your Bluetooth device for an extended period, turn it off to maximize battery life. To turn it off, use the on/off switch.