DO NOT contact a college or university. They will, in turn, contact state and Federal authorities regarding the possibility of "significant cultural resources" being present on your property and then you will have a world of grief on your hands.
The cost of acquiring a ground penetrating radar unit and an operator is astronomical. Unless you are 100% sure there is something there, Don't.
It's on your property and it's yours if there is anything there at all, but if you tell a lot of people, someone will try to get involved and try to claim jurisdiction (State Historic Preservation Officer, or possibly one or more Federal agencies in the name of historic preservation and concervation concerns). So whatever you do, keep quiet about it.
Do the work yourself, it's not difficult. First check the local library for old maps and records. If the story can be verified, then there might be a chance that something is there, but even if it can't be, it wont hurt to explore the area.
First, remove the rubble by hand with the help of family or friends. Since it's on private property and no one has access, you are in no hurry, make it a summer project or longer. If it turns out that there is a cave and the rubble is covering the entrance, then you get to explore it and claim what is there without any outside interference. If the cave is completely filled in with rubble, then by the time you clear it you will have discovered if there is or isn't anything in it.
Just remember, professional treasure hunters are in it only for the money. University, State & Federal Archaeologist don't want anyone other than themselves to have anything to do with archaeology and will try to either cut you out of the picture or confiscate anything you recover and don't listen to the hype about how only trained professionals are the only ones who can do what you want to do, that's B.S. Once you get started, you'll enjoy it and wonder why you didn't do it sooner. Have fun and good luck.
DesertRat