Jailbreaking iPhones requires applications designed for the purpose; a popular and reliable one is Pangu 1.1. Download the application by visiting the Pangu website, and selecting the option that fits your electronic device. This application jailbreaks all devices that run on iOS 8, including the iPhone 6.
Before starting the jailbreak process for the iPhone, back up the data on the phone by going to Settings, then iCloud, then Backup and selecting Back Up Now. After the data is backed up, disable the passcode by going to Settings, then Touch ID & Passcode, and disable any passcode you're using.
Next enable Airplane Mode by opening Control Center and tapping on the airplane icon. Then download the Pangu 1.1 application to jailbreak the phone. The iTunes app is also required to complete the jailbreak. Once the Pangu 1.1. app downloads, open it and then plug in the iOS device to be jailbroken. Once the device is recognized by the application, select the Start Jailbreak option and then click Already Did. After the app runs completely and the iPhone reboots, close the Pangu application. Then tap the Cydia icon to prepare the file system. After this step, the iPhone is finished with the jailbreak process and is ready for use.