"Impeachment" is a word that is frequently misunderstood. Here's a brief definition from Wikipedia:

"Impeachment in the United States is an enumerated power of the legislature that allows formal charges to be brought against a civil officer of government for crimes alleged to have been committed. Most impeachments have concerned alleged crimes committed while in office, though there have been a few cases in which Congress has impeached and convicted officials partly for prior crimes.The actual trial on such charges, and subsequent removal of an official upon conviction, is separate from the act of impeachment itself."

https://en.wikipedia.org/wiki/Impeachment_in_the_United_States