Banannie,
First of all congrats on the combo interview down there. I think you'll love Durham and Chapel Hill.
Though I am a grad of Duke (not in medical school there nor planning on it since Duke gave me the official alumni rejection 🙁 ) I know the area a little bit. You can take the Robertson Scholars Bus which runs all day between Duke and UNC. The Duke bus stop is right off the main quad, where the medical school rests off of. That bus takes you to the UNC Planetarium on Franklin Street. I don't know exactly where the medical school is at UNC, but I'm sure that it's not too far from there, I think it's a couple of blocks north of Franklin Street near the Dean Smith Center. Everything is pretty close once you get to Chapel Hill. The Robertson Scholars bus is free, just ask some of the undergrads waiting at the bus stop when it comes. I know it comes every hour, probably twice an hour at the very least if not more. But, make sure you get on that bus, and not an East-West or Central Campus bus, that'll just take you around the Duke campus.
Good luck! I hope this helps.