How to activate Google now voice commands from the lock screen like siri? I just switched from an iPhone, and I want my android to have the same behavior as iOS where you hold the home button, and siri starts listening. 

With my android, I have to wake up and unlock the device, then hold the home button to get to the google now screen, then I have to either say "okay google", or hit the microphone button. 

This process takes way longer and makes voice commands in the car unsafe, which is primarily what I used siri for

Please any help would be appreciated
In Google Now, click the menu icon on the left of the search bar (it looks like a hamburger).

Then choose Settings -> Voice -> "OK Google" Detection.

(Click image to enlarge)



Flip the three switches on. When you switch on the second one, the app will ask you to say "Okay Google" three times to train the voice model. Flipping the third switch on will prompt you for the password to your phone.

Now, when you say "Okay Google", the screen will be unlocked.