Displacement Module

Is there any module that can measure displacement?

Actually I am making a obstacle avoiding robot that can reach to a desired location for that purpose any module that can measure displacement so, Robot can go to desired location without the human help. Initially I thought about GPS module but it's accuracy is 1 meter which is useless I need something of accuracy upto 10cm.
Consider the fact that I am working on high school project

Pozyx can do this.

It's too expensive i am working on school project, consider that fact

Then you have to create a different project, or develop a cheaper way to do this positioning yourself (which, considering it's a school project and you have to ask here, is quite certainly way above of your skill level).

This kind of positioning is really hard. It's not just because it's not cheap, or that not many other people have been able to develop a working system.

It's too expensive i am working on school project, consider that fact

Consider doing a cheaper project.

The solutions to this problem are all fairly advanced technology, SLAM, UWB, differential GPS, IR camera array.