Microman is Tim Smalls. As a kid he was always bullied by Jeff Towers. Tim Smalls got the name Microman from his childhood bullies. To get back at them he started getting in to crime and robbing homes. Microman thought that because he was small he could use that to his advantage to rob houses and not be seen easily.
Since Microman grew up in the City of Los Angeles he is familiar with the neighborhood and the streets and where the police hotspots are. He is a small thumbtack according to the police. We can not see him or find him says the police chief. If he is touched by anything larger than him he will die.
Microman has turned to crime to get back at his childhood bully Jeff Towers or Macroman. His bully was very tall and popular so this hurt Tim even more. He wants to show he has power against his enemy Macroman and eventually take over the city of Los Angeles to show power