attach Hexagonal Grids to a terrain like a texture

Hi. I am creating a terrain with unity. I want to attach a clickable hex map area to this terrain that look like a texture inserted in to it. something like this:

I even can convert terrain to mesh if you have any solution for that.

exactly I want to map a Hexagonal grid area to a terrain or mesh that have many Hill or pit. and I can not use texture , because I want to be able to click on each hex. and if you know any package or plugin that can do this for me. please tell me.