I want to marker/paint my object

I already seen this

tutorial to make marker/painting but the paint is flying and what I want is this marker is intact within my object. How can I do that, can anyone help me?

 

Do you have any experience in making VR application?

 

No, I do not have any experience at all

 

If you want to do VR application, you need split problem into multiple smaller problems.
In this case, VR and the application mechanics like painting are quite separate problems, yet strongly related.
You will have hard time to find complete solution.
But you may be able to find solutions to individual problems.

In your case, you need detail the problem you are trying to tackle.
Asking how to make full application from A to Z, is not what you will find helpful.

If you however are new to Unity all together, this problem may be too big to chew at once for you.
And you need significantly scope the problem down.

 

Well, you need to get some experience with procedural geometry and textures.

Long story short, there are two ways to "paint". You either paint on object's texture, or you make more geometry.

For example, stuff like gravity sketch essentually spawns polygonal ribbons which follow the tip of player's controller. The ribbons are splines.

But you also can use metaballs (though this one can be quite computationally heavy), or voxels (again, can be computationally heavy), which will be used as a base to produce polygons.

Also, when painting on texture, you can implement "projective painting" in which case you'll be pretty much controlling a spray can.

For all of those approaches you need some experience with 3d.

For example, can you make an application which allows user to create a parametric torus? Create it, move it, rotate it, specify its radii then specify number of segments it uses?

If you can, then you should be able to implement your painting application.