Apple introduced "rootless" technology in its new operating system iOS 9 with a purpose -- to prevent hackers from jailbreaking by blocking access to iOS root -- but it seems the firmware is already broken.
It is still not known when complete iOS 9 exploits will be released. iH8sn0w, developer of popular jailbreak tools such as Sn0wbreeze, P0sixspwn and iFaith, has released a video showing an untethered iPhone 5 running a jailbroken iOS 9 on his YouTube channel but the tool needed to jailbreak has not been made public.
The only option to jailbreak iOS 9 at the moment is Semi JB's partial jailbreak. However, you can only install the Cydia with limited functions.
Here is a step-by-step guide to jailbreak iOS 9 with Semi JB method (source: Semijb website):
[IBTimes India will not be held liable for any damage to your device during the process. Jailbreak your device at your own risk]
Step 1. Use safari browser on the iOS device to jailbreak iOS 9
Step 2. Go to semijb.com using safari browser and tap jailbreak now button. It will redirect you to installation page according to your iOS version
Step 3. Wait for Semi jailbreak to detect your device
Step 4. Start jailbreaking process by tapping "I agree to continue" button.
Step 5. Allow semi jailbreak to run the commands and don't exit from the browser till it's done
Step 6. You should get a message that says semi jailbreak process is done before being redirected to install Semi JB profile to access the download data. Now, apple will warn you that it is not verified. Ignore it and install the app.
Your device should be running on jailbroken iOS 9 now.