How to move the vertex ?

Unity Engine
1

how to determine the position of the vertex and move it ? Without RaycastHit.triangleIndex

2 
    for (var  i=0;i<vertices.Length;i++)
    {
        sqrMagnitude = (vertices[i] - position).sqrMagnitude;
         //sqrMagnitude = (vertices[i]-position).sqrMagnitude;
        // Early out if too far away
            if (sqrMagnitude > sqrRadius)
            continue;           
        //    vertices[i] +=  ((Vector3.forward*maxDeform)  * power);
           
        //}

        vertices[i] =  vertices[i]+Vector3.up * heightDeform;
        //vertices[i].z = heightDeform;
           
    }

I change the position of the vertex, but the same vertices do not change their position. Vertices are moved, if they have not moved . Why?