As well as picking up sounds in the air a microphone will also “hear” sounds that pass through its body, cable, or even from the desk it is resting on. This mechanical transmission means if you bump the microphone, drum your fingers on the desktop, or even set down a cup, that sound will appear surprisingly loud. Some microphones include a rubberized foam layer on the base of the stand, such as the one on the Blue Yeti. This helps to acoustically isolate the microphone from the desktop and so minimize those sounds. You can also mount the microphone in a shock-mount on a boom arm. The boom arm allows you to place the microphone wherever you need it and stock it is getting bumped. The shock mount isolates the microphone from the boom arm so that any sound vibrations passing through the boom arm do not reach the microphone.     If your mic is picking up sound from your desktop the cheapest solution is to buy some anti-vibration stiff rubber foam pads and place your mic and desktop stand on the pad. The pads are often used under big appliances like refrigerators and washer/dryers.