If the slope changes tend to be slow such as soil creep, you might try ground based LIDAR.or just periodic total station surveys of ground points (x, y and z coordinates) for surface changes.  Ground penetrating radar monitoring and mapping may help with with the subsurface changes.  A research geologist may have other ideas beyond these.

Thanks Prof. William F. Hansen.

However, what I mean that I have the result of displacements (x, y and z coordinates) by monitoring, I want to use (x, y and z coordinates) to calculate the properties of ground layers. What should I do?

Thanks.

Dear Kien,

Your question is not clear.

"........... to calculate the properties of ground layers".

What properties you like to investigate?

Read the attached paper - discussion on soil properties and slope. May be of your interest. Regarding soil properties, you can see the following link.

https://www.nrcs.usda.gov/wps/portal/nrcs/detail/nj/home/?cid=nrcs141p2_018993

Best Wishes

Thanks Dr. Asit Kumar Batabyal very much!