how to know position to gameobject's exist?!

hi
i had a headache becasuse of this question
please help me T.T

Q.
i know one vector3 position
ex) vector3 po = new po(1f, 0.5f, 3f);
i want to how to know this postion to gameObject’s exist?!
please

I think you are looking for OverlapSphere.