How to hack the Computer using Hardware Keylogger?

So far we have seen about the Keylogger software, now i am introducing Hardware key logger to my readers.  If you don't know about key logger ,please read this article.

What is Key logger?
What is Malicious softwares?


Drawbacks of Key logger Software: 

   Easily detectable
   User can block the Key logger Software using any Security system.

Key logger software captures each key strokes.