Just like in iOS 11, you can enable Type to Siri in macOS High Sierra. This is a feature that lets you type queries to Siri, just like you would a search engine. It’s useful for people who may feel awkward talking to their iPhone or Mac. It’s also helpful in certain situations where silence is a virtue, like in a library. Here’s how to turn in on in macOS.
Type to Siri
Open System Preferences, then go to Accessibility. Scroll to the bottom and click on Siri in the left sidebar. You’ll see a checkbox that lets you turn on Type to Siri.
Next, you can go back into System Preferences and click on the Siri icon. You can enable or disable voice feedback, for ultimate silence.