Transform Position

Hello. For a school project we had to create our own Vector 3 In unity and use it later to move objects. The goal was to make a sphere move to the position of the cube using our own vector and the subtraction of vectors (SubtractVector Function). But every time I try to set the destination of Sphere to the one I calculated on the SubtractVector function it shows me an error of "Cannot implicity convert type "MyVector3" to "UnityEngine.Vector3". Can someone give me some help..?

My code:

     public GameObject Cube;
     public GameObject Sphere;
 
     private void Start()
     {
          Sphere = GameObject.Find("Sphere");
 
          
     }
 
     private void Update()
     {
         Vector3 test = new Vector3(1, 1, 1).normalized;
           
 
         
         if (Input.GetKeyDown("space"))
         {
 
             MyVector3 cubePos = new MyVector3(Cube.transform.position.x, Cube.transform.position.y, Cube.transform.position.z);
             MyVector3 spherePos = new MyVector3(Sphere.transform.position.x, Sphere.transform.position.y, Sphere.transform.position.z);
             
             MyVector3 move = MyVector3.SubtractVector(spherePos, cubePos);
 
 
             Sphere.transform.position = move;
 
 
 
         }
 
        
     }
 }

Own Vector code:

  public float x,y,z;
 
     public MyVector3(float x, float y, float z)
     {
         this.x = x;
         this.y = y;
         this.z = z;
        
 
         
     }
 
   public static MyVector3 SubtractVector(MyVector3 vec1, MyVector3 vec2)
     {
         MyVector3 rv = new MyVector3(0, 0, 0);
 
         rv.x = vec1.x - vec2.x;
         rv.y = vec1.y - vec2.y;
         rv.z = vec1.z - vec2.z;
 
         return rv;
     }

Thank you.