And most important, you can disable "Hey Siri" trigger on your iPhone/Mac or Apple Watch. If you disabled "Hey Siri" trigger (and left "Siri" on) then you have

And most important, you can disable "Hey Siri" trigger on your iPhone/Mac or Apple Watch. If you disabled "Hey Siri" trigger (and left "Siri" on) then you have to long press "Home" button (or button on the right, if you are on iPhone X and later) to start "Siri"