iOS 8 comes with a Google Now like feature called “Hey Siri.
It allows you to invoke Siri without pressing the Home button.
But there is a catch. The feature only works when your iPhone is connected to a power source, most likely to conserve battery life. It doesn’t do anything when the device is unplugged.
Here’s how it works:
All you need to do is connect your iPhone to a power source, and say “Hey Siri”. It should bring up Siri.
It is a nifty feature when you’re driving to get directions, send an SMS or make a phone call, and don’t want to take your eyes off the road trying to press the Home button to invoke Siri.
You can enable or disable this feature via the Settings app (Settings > General > Siri > Allow “Hey Siri”)
Let me know how it goes in the comments.