AirPods
Will the AirPods 1 fit in the AirPods 2 case
Question marked as
They may fit, but they probably won't work (all the serial numbers must match) unless you have followed the steps in the 'Replace a missing AirPod or charging case' section of:
Find your lost AirPods - Apple Support
and
Set up your replacement AirPods or charging case - Apple Support