Move the screen when object close to screen borders.

Hi. I'm new in Unity. I have a script which can move background with parallax effect.infinitely. If i attach the main camera to the object. when i move object camera and background moves. but i want to drag object in screen. but for reason main camera moves with the object, it seems like it doesnt dragging. i deattach the camera from the object. but then i can drag it but background doesnt scrool. i wanna drag object and when object arrrives border of the screen (vertical +1 or -1 value) , then background must start scrooling.see the picture.thank you.