Hello I want to use my phone as a camera in my drone so what are the steps to install it and how can we connect it to my drone. Pls help me

What do you mean by "connect"?
As in connecting mechanically or electronically(fpv)?

I think  he wants to use the transmitter to control the phone cameras shutter to be able to take pictures from the ground . Ideally use the tx also to switch between video and still modes.

I too want to know if there is a way of doing this as I have several old phones that have quite decent cameras.

Of course the holy grail would be if there is a way to extract the camera from a phone and use it in a drone.

@Pranjal.bala
I don't know equipment and accessories are present for this.
But you want to do DIY Project then
first of all, You have to make your own custom app for this purpose & you need to make a system that can send commands to your mobile. App will understand commands and capture images & will record video for you.
You can use Arduino to send data via usb cable.

Many people made diy simulator system with arduino.

And why you want your phone as camera? if drone will crash, then your mobile can be damaged.

@saikat sir
Why you want old camera from phone for drone?
Now all people want HD.

All the members i am very sorry but i am a noob in RC stuff i have build my drone DJI450 and i don't have camera so i thought why not to use my phone as a camera for my drone.

There is one way to do so , but you will need 2 phones one to install in the quad while the second one to control the first one. Firstly install ip webcam app or any similar app , then switch on the hotspot of one phone and connect the second one to that network. Open the IP webcam app and start streaming , till both of them are connected on the same network you can control the first phone to take photos and videos are saved in gallery. Hope this helps
Regards

The range is not that great till you use some equipments to extend range.

@knvshrm
Wifi hotspot range is about 20 meters.
https://www.quora.com/How-far-does-a-mobile-phone-WiFi-hotspot-reach

@Pranjal.bala
DJI450 with dji motor and dji all things?

DJI450 with brushless motors and with openpilot flight controller

Can you explain this in detail? What equipments?? Please

http://m.buy.mi.com/in/item/3172400004
Use this is  a xiaomi WiFi repeater increases the strength drastically it weighs only 30g. It's available for 799 in India. Just connect this to your phone with a normal USB cable.

Also there is another app through which you can connect to any phone no range limit through the app. If you use that you'll be able to control the phone and you don't need the wifi repeater . The name of the app is Alfred  home security. You just have to login with the same email on both the devices and no range limit so you view it from anywhere. Also this has many other features like motion sensor etc.
Regards

There are a lot of internet cam apps.

why not attach your phone to the quad; have it video the whole flight.
If you want a specific picture, take it out of the HD video later on when using your Computer.
If you want to live stream, what i did once:
one phone on plane, one with me. Both have skype and good 4G network coverage. I make a skype video call from one phone to other. Though, i always keep my plane near me (LOS)
Better if you get dedicated FPV equipment. Its not that expensive.
Print the mounting for your phone using a 3D printer.
Regards.