How to perform noise cancellation with mycroft

Hi All,
I have installed picroft within my raspberry pi. Now when i come things it always take my word and if it could not understand it replies with me Sorry I could not understand what you say. So thus mycroft will be always listening.

Now my question is i want behavior where it would in active mood only when i say hey mycroft, So that i am not talking to mycroft it would be in off or sleep mode.

I am giving example of Amazon Echo or echo dot. So when I say Alexa then and then only it listen to me, other wise if i am talking another thing it will not wake up.

I want same behavior with my picroft. How Could I Achieve it . Please Help Me