OpenMV Distance Shield can measure the distance to obstacles within 4 meters range with 1mm accuracy.

The distance shield uses a TOF (Time of Flight) sensor chip, which measures distance by calculating the time it takes for light to travel to and reflect back from objects.

Compared to ultrasonic sensors, TOF sensors have a much narrower field of view and higher precision.

Compared to measuring infrared light intensity, TOF sensors are more accurate, and unlike infrared sensors, they can reliably distinguish between near and far distances.

Tutorial

OpenMV Distance Shield