Heavily damaged iPhone 8 unable to back up

The screen is so far gone and I was hoping to back up the phone. Before the screen went completely dead, a portion of the screen appeared to be the disabled screen. I tried plugging into 2 different pc's and the phone wont appear in iTunes but still vibrates like it "knows" its now connected to a computer. How can I back it up or extrapolate the data that's on the phone?