Yes they are being trained for this. They wear a little back pack and can signal back to base with a button.
There are are Gambian Pouched Rats for mines, TB testing etc, they're not as easy to keep as Norwegians.
I have 4 fancy Norwegian rats. They are easily the nicest creatures I've ever owned.
The downsides are their lifespan - 2-3 years so you are endlessly heartbroken, and the vet bills.