One of the most accurate type of distance measuring sensors are the laser sensors, with reading errors not exceeding a few millimeters. These sensors can do distance measurements as well as speed and acceleration readings on certain objects with respect to the mobile robot. They operate by sending a pulse of light into the environment and measure the time until it is received back at the sensors, then distance is calculated.
The maximum range of a laser sensor can vary from hundreds of meters to hundreds of kilometers. This very same technology is used to do measurements between celestial objects with great accuracy.
These capabilities come at a cost, a laser sensor is very expensive so the need for such accuracy must be highly justifiable.