Two things seem to work well. Pour amonia (full strength) down the hole or pour used cat litter down the hole. Either way groundhogs hate it and will abandon the area. Since I live in a rural area and am plagued with groundhogs borrowing under my in-ground pool, I get rid of them with my .22 hornet. I’ve recycled 7 so far this spring...
Will the ammonia work for moles? It would be a lot less expensive than spreading grub killer granules.