That obviously depends on what sensors you buy, or (if you design the solution yourself) what solutions you chose.

For a raw ultrasound system, you normally measure time. But you can buy complete systems that has a serial port or similar where you get ready data in text form.

For a light beam system, it will be the equipment that moves the beam that decides what signal you get. Having a linear potentiometer would mean that you could measure mV. Counting ticks on a stepper motor could mean that you just keep track of number of steps in relation to a zero switch.

Using a laser or similar and project a pattern and picking up the pattern with cameras would mean that you have to compute the position of the projected pattern in the projected space, and then transform into a normalized space.

You really have to spend time narrowing down what you want to do. There are too many possibilities and depending on what hardware you have around the sensor will greatly affect how you will get the reading.