How to check if an object of objects is inside a spherecollider

Hi guys,
I have a cylindrical object which has a sphere collider attached to it (think a tower, with a attack radius). I want to know what code I use so that the tower detects if an enemy is inside its range. Thanks guys,

You can make the sphere collider a trigger and use OnTriggerEnter() to detect and recognize any object which has entered the attack radius (in this case the sphere collider). Make sure that the objects to be detected have a collider.