How can I get a GUI Label to follow a moving game object when the player camera is stationary?

So quick context: I'm making an app that takes a panoramic, 360 deg image and allows the user to view it as if they are in the center of that pan. I've done this by creating a sphere, placing the image on the inside of that sphere and placing the camera at the origin of the sphere. Now I have a small cube that slowly moves along the boundary of that sphere, like a satellite orbiting the earth. How can I make it so that clicking/tapping the cube causes a label to pop up and follows the cube? I've been able to get a GUI label to pop up upon clicks, but the label position stays stagnant and in camera view. I've tried making it a function of the cube's rotation, but I can't get it to detect the click on the object.