Siri can be a useful assistant on the Mac and easy to access the information needed by just using voice controls. However, there are times when talking out loud to the Mac is inconvenient or unsuitable e.g. while in a meeting or in a library.
Apple has added an option in High Sierra that enables interaction with Siri without requiring voice commands, the method of input is via typing commands or queries in to Siri.
First, select the System Preferences icon, I keep mine in the dock for easy access (img.1).
Once the System Preferences window displays you will see an Accessibility icon in the bottom right of the window, you should now click on this (img2).
In the Accessibility window scroll down on the left and select the Siri option, then tick the checkbox ‘Enable Type to Siri’ (img.3).
Now when the Siri icon is clicked a text entry box is displayed for a command or query to be entered (img.4)
Remember to turn down the volume so you don't hear the response out loud.
An easy way to use Siri on Mac without using voice.