How get Mesh height after shader deformation ?

Hi everybody,

I'm using shader graph to make an ocean. My shader modify vertices height to make waves.

Now I wanna create floating object wich react to waves. I don't want to use a collider on my ocean for performance. But I need to get height of my mesh at some points...

Do you know how can I get it from my shader or from a script ? Does existing a sort of ray casting for non-collider object ? Thank you for all =)