1 public class CustomEventArgs : EventArgs
   2 {
   3     private readonly object item;
   4 
   5     public object Item
   6     {
   7         get { return item; }
   8     }
   9 
  10     public CustomEventArgs(object item)
  11     {
  12         this.item = item;
  13     }
  14 }

   1 public delegate void NotifyCustomEvent(object sender, CustomEventArgs e);
   2 public event NotifyCustomEvent CustomEvent;
   3 
   4 private void RaiseCustomEvent(obj sender,  obj item)
   5 {
   6     CustomEvent?.Invoke(sender, new CustomEventArgs(item));
   7 }

   1 public InsanceOwner()
   2 {
   3   Instance instance = new instance();
   4   instance.CustomEvent += new Instance.NotifyCustomEvent(CustomEventHandler);
   5 }
   6 
   7 public void CustomEventHandler(obj sender, CustomEventArgs e)
   8 {
   9     //Handle that custom shit
  10 }