Custom vibration patterns found their way to iPhones since the iOS 7. To create custom vibrations on iPhone 5, iPhone 6 and others iOS devices, do as follows:
1. Open the Settings application and go to the Sounds settings
2. Scroll down and tap the Ringtone option, under the Sound and Vibration settings.
3. Tap the Vibration option
4. By default your vibration pattern is set to default, and you have the option to use the already existed vibration patterns, or go for the create custom vibrations option
5. To create a new vibration pattern, tap the Create New Vibration under the Custom settings and start tapping the screen to create your custom vibration pattern on iPhone (You may tap and hold your finger on the screen for a more strong custom vibration pattern)