When you mouse over a character or creature in the game that is currently targeting something, it shows a second, small tooltip attached to the main tooltip with their target's name, level, and other info.
/simplemousetarget
toggle - toggle show / hide
on - show
off - hide
red - toggle turning the background of the second tooltip red if the target is the player
green - toggle making the second tooltip green if you are targeting the same the target
pos # (1-12) - relocate the second tooltip around the gametooltip.
Update of original addon from Vanilla wow for Classic Era, found here:
https://www.wowinterface.com/downloads/info12361-SimpleMouseoverTarget.html#info
All Credits to original author Brodrick.

