I have 6 inch borewell of 1200 feet (domestic use). With camera test, we could see water storage is at 960 feet. i.e approx storage of 200 feet. i.e around 1000 liters. my question is, can we put motor? will it work? What happens if we pump and water is just enough for pipe above? after we stop motor, will it discharge water back or will it hold in pipe and next pumping will push out?
You cannot possibly use any pump with suction at that depth. You must have a multistage submersible pump. This would be a small ESP in the oil industry where liquids are pumped from as deep as about 15,000 ft with over 100 pump stages. A good domestic water well company will have some applicable pumps and check valves. You will need some serious electric power and equipment to install and recover the pump for service. You may need "pump off" control to shut off the pump when the water level drops too low and other things . It sounds like you need an actual engineer to set it up.
You should be able to find submersible motor / pumps for this and most, if not all, will have a one way valve to stop the backflow, this means delivery is quick when the motor is turned on.
You just need to source one that will work at the pressure created by the depth.