Adding a listener to bar's on a bargraph issue...

I'm trying too add a listener too this gameobject but I'm not really familiar with listeners and I got this code from another post so I'm probably not implementing this correctly. could someone help me out here? I've been trying to figure out how to get these objects to be detectable when the mouse moves across it so I can run a tooltip function that display's the bar graphs value.

         private GameObject CreateBar(Vector2 graphPos, float barWidth)
 {
     GameObject gameObject = new GameObject("bar", typeof(Image));
     gameObject.transform.SetParent(graphContainer, false);
     gameObject.GetComponent<Image>().color = barColor;
 
 
     gameObject.AddComponent<Button>();
     gameObject.AddComponent<Renderer>();
     gameObject.AddComponent<EventTrigger>();
     EventTrigger evtTrigger = gameObject.GetComponent<EventTrigger>();
     // On Pointer Enter
     EventTrigger.TriggerEvent trigger = new EventTrigger.TriggerEvent();
     trigger.AddListener((idObject) => { gameObject.GetComponent<Window_Graph>().ShowTooltip(); });
     EventTrigger.Entry entry = new EventTrigger.Entry()
     {
         callback = trigger,
         eventID = EventTriggerType.PointerEnter
     };
     evtTrigger.triggers.Add(entry);
     // On Pointer Exit
     EventTrigger.TriggerEvent trigger2 = new EventTrigger.TriggerEvent();
     trigger2.AddListener((eventData) => { gameObject.GetComponent<Window_Graph>().ShowTooltip(); });
     EventTrigger.Entry entry2 = new EventTrigger.Entry
     {
         callback = trigger2,
         eventID = EventTriggerType.PointerExit
     };
     evtTrigger.triggers.Add(entry2);