There are a few records of burrowers such as Lysiosquillina living with small clearner shrimps. In the burrow entrances of both Lysiosquilla and Hemisquilla I often find ostracods. There is also a snapping shrimp that is reported from the burrow of a squillid.
There are also reports of small Nannosquilids living with the proboscis worm, Balanaglossus, but in this case I think it is just a matter of the burrows being entertwined. Most other cases of stomatopods found in the burrows or cavities of other animals are probably cases where one or the other dove for cover,
I know of no case where a stomatopod and a fish live commensally.