USB 1th s asic bitcoin miner miners are available to buy, but they don’t really generate any significant profits. You should buy one to learn how mining works, but other than that don’t expect much! There is USB Bitcoin mining hardware, which mines bitcoins. Both are USB type devices that have completely separate functions!
The Sapphire Block Erupters were the first Bitcoin USB miners. It may be a good choice just to see how mining works, but like with most USB miners: do not expect to turn a profit. 15 per month, which is more than a dollar per year! The company claims that the device runs completely silent.