Spawning different prefabs randomly using Object pooling

I want to spawn 3 different types of prefab randomly through pool manager script. I found the given script when I access this script in cube Spawner script but Here It doesn't take more than one prefabs sorry for weak English .If any one get my point help thanks. Dictionary> poolDictionary = new Dictionary>(); static PoolManager _instance; public static PoolManager instance { get { if (_instance == null) { _instance = FindObjectOfType(); } return _instance; } }

 public void CreatePool(GameObject prefab,int poolSize)
 {
     int poolKey = prefab.GetInstanceID();
     if (!poolDictionary.ContainsKey(poolKey))
     {
         poolDictionary.Add(poolKey,new List<GameObject>());
         for(int i = 0; i < poolSize; i++)
         {
             GameObject newObject = Instantiate(prefab);
             poolDictionary[poolKey].Add(newObject);
         }
     }
 }
 public GameObject GetObject(GameObject prefab)
 {
     int poolKey = prefab.GetInstanceID();
     if (poolDictionary.ContainsKey(poolKey))
     {
         List<GameObject> pool = new List<GameObject>();
         for(int i = 0; i < pool.Count; i++)
         {
             if (!pool[i].activeInHierarchy)
             {
                 return pool[i];
             }
         }
         GameObject newObject = Instantiate(prefab);
         poolDictionary[poolKey].Add(newObject);
         return newObject;
     }
     return null;
 }

Bellow is the script where I want to spawn different prefabs.

private void Awake() { currentPosition = cubePrefab.transform.position; } private void Start() { PoolManager.instance.CreatePool(cubePrefab, poolSize); InvokeRepeating("SpawnCubes",0f, 10f); } private void SpawnCubes() {

     GameObject cubeObject = PoolManager.instance.GetObject(cubePrefab);
     cubeObject.transform.position = currentPosition;
     cubeObject.SetActive(true);
     Vector3 newPosition = currentPosition;
     newPosition.z += distance;
     currentPosition = newPosition;
   
 }