Use Unity's Render to Texture capability to create a camera in your scene. Then create a new Render Texture and assign it to that camera. Then create your screen in your control room and assign it to that Render Texture. You will then see the camera view through the texture.
Since you can't use Render textures with Unity free, you could create a pop up window for the camera screen. Let me explain. The player would walk up to the monitor and hit a key to turn it on. Then another camera rendering the outside area would be put in front of the current camera like a pop up window so that when the user moves the camera outside, the pop up window will display that. If you want to you could also add a border around the camera using GUI stuff to make it look nice.