How to make object clickable when user enter collider ?

Hi, I'm new to Unity.

May I know how can I make an object is clickable for showing text when user enter the collider?

I used OnMouseDown() but the object will show the text even I'm outside of the collider.

Below are some of my coding. May I know how I can correct it ? Thanks.

 void OnMouseDown() {entrance = true;}

 void OnTriggerEnter (Collider col)
 {
         if (col.gameObject.tag == "Player")    {
             entrance = true;
     }    
 }
     void OnTriggerExit (Collider col)
     {
         if (col.gameObject.tag == "Player")
         {
             entrance = false;
         }
     }