Do you want the output of the OP-AMP to signal a ‘HIGH’ or ‘LOW’ to the microcontroller?
If yes, you can connect the output of the OP-AMP to the base of a transistor via a resistor and the collector of the transistor (also connected to 5V vcc) to your microcontroller. The transistor will then allow you to get 5V and GND on your microcontroller pin.