Arduino Micro Interrupt
If there is a way to make pin 12 on the Arduino Micro an Interrupt pin


you should take a look at the device datasheet and see what other functionalities pin 12 has. 

if it is a pcint pin, you are golden;
if it is a timer input pin or an input capture pin, they can be programmed to act like an interrupt pin as well.

all begins with reading the datasheet.