Cannot connect beagle bone black to my PC running Ubuntu 16.04

Not able to SSH into Beagle bone black to its default IP ( over USB.
Also in /dev mount point it’s showing ttyACM0 instead of ttyUSB0.

Note: It’s running perfect on Windows pc.

Device: Dell Notebook
Operating System: Ubuntu 16.04

SSH from where
but its running perfectly on windows ?

It hasn't flipped over to using has it?