Ball Rotate Around Cube

Take a look at this first

A little bit of modifying and your script is ready to go

 using UnityEngine;
 
 public class ExampleClass : MonoBehaviour
 {
     public Transform target;     //Assign Cube in the Inspector
     public float speed = 20.0f; 
     void Update()
     {
         transform.RotateAround(target.position, Vector3.up, speed * Time.deltaTime);
     }
 }

or if you want it to "stick" around the cube Add this script to the Cube :

 using UnityEngine;
 
 public class Gravity : MonoBehaviour {
 
     public float gravityRadius = 2.0f;
     public float gravityForce = 100.0f;
 
     public void FixedUpdate()
     {
         foreach (Collider collider in Physics.OverlapSphere(transform.position, gravityRadius)) {
             Vector3 direction = transform.position - collider.transform.position;
             collider.GetComponent<Rigidbody>().AddForce(direction.normalized * gravityForce * Time.fixedDeltaTime);
         }
     }
 }

Note: in this case both object must have a Rigidbody. Cube rigidbody is IsKinematic = true and useGravity = false. Spehere useGravity = false... At least for the testing :)