Where have you heard or read about this USB bitcoin miner? For you to mine Bitcoin, you need an ASIC miner and that's not as little as an USB.

I do believe that you've watched a video like this: --> https://www.youtube.com/watch?v=_aEMh4esWBU&t=108s "Solo Mining Bitcoin with AntMiner USB Stick on Raspberry Pi"

At the end of that video it says that it's a lotto mining and mostly a gamble. And that USB is even going to be hotter that you barely touche it based on what the guy said on that video.