Saw someone blatantly cheating on our final using their phone — not sure what to do…

I was taking a final today and I saw the girl in front of me very blatantly take out her phone and use it the entire time for the test… I kind of don’t want to fuck someone over for the rest of their academic career, but I know what I saw, it was the ENTIRE test that she was on her phone. She had it in her lap and I would see her type and then write down the answer. I don’t know her name, just what she looks like. I don’t want to be a snitch, and I think if it was just once I would’ve been fine and looked the other way, but it just feels unfair to let someone get possibly a better grade than me because she was using her phone the entire time. I’m not sure what to do and was hoping for some advice…