Is it possible to hack the computer via USB ?

I am thinking about the security problem on open wifi, my computer could get hacked when connect to unfamiliar open hotspot. I wonder if it would be safer to use USB dongle instead of the build in wifi, so that the best the hacker can do is to see the dongle and it's MAC instead of seeing the internal wifi of the computer and go deeper ? I know nothing about the hacking thing, just a random thought pops up on my mind.