using System.Linq;
----------
GameObject[] hh = Physics2D.OverlapCircleAll(transform.position, 12f).Select(a => a.GetComponent<GameObject>());private int oldValue;
void Start() 
{
    oldValue = 42
}
void Update()
{
    if (oldValue != newValue)
    {
        OnValueChanged(newValue);
        oldValue = newValue;
    }
}
private void OnValueChanged(int newValue) 
{
}