There are many.. CAMPING WORLD sells a plastic thing that mounts on the fridge (you need to drill some holes) and it does a fairly good job.. I used one on my fridge at home.
You can also use any common door latch, hasp, hook and eye, Lots of options.
When I was trailering I had a compact (Office/Dorm) type fridge and I simply put a packing strap around it,, Had a couple more attached in a specific way so they formed a handle so i could pick it up. Used that thing for several years and sold it to another camper when I upgraded to the A.
