Direct from https://support.apple.com/en-ca/HT208718:

Use AirPods with a non-Apple device

You can use AirPods as a Bluetooth headset with a non-Apple device. You can't use Siri, but you can listen and talk. To set up your AirPods with an Android phone or other non-Apple device,3 follow these steps:

-On your non-Apple device, go to the settings for Bluetooth and make sure that Bluetooth is on.4 If you have an Android device, go to Settings > Connections > Bluetooth.
-With your AirPods in the charging case, open the lid.
-Press and hold the setup button on the back of the case until you see the status light flash white.
-When your AirPods appear in the list of Bluetooth devices, select them.