Electrical breaker keeps tripping

First time user so I'm hoping I'm posting this in the correct area. I'm having an issue with a breaker popping after we had a fence install done. What happens is any time it rains, the breaker trips for the electric that runs to the garage. It usually takes maybe an hour or two of rain before it trips. If we pop it back on after the rain stops, it will stay on until the next rain. We are thinking that during the fence install they may have nicked a wire underground. Because during the install, the breaker also tripped (first time it happened), but we reset it and was fine and thought nothing else of it until it rained. We don't know exactly where the underground wire is, because we had just purchased the house last year. I'm wondering if this sounds reasonable that this may be what's causing it? Or could it be something else? I had one guy come to give an estimate and he left without actually giving an estimate, and was talking about digging straight out the gate, and stating it could be that or something else. Isn't there a device that will tell you if there is a nick in an underground wire (leaked voltage or something like that) before tearing the yard up? We know the general area they were working when it tripped during the fence install. The guy seemed kind of all over the place and just want to make sure we are informed and don't go paying someone to dig up the yard if it's not even what the problem is.