Sometimes it’s not practical to ask Siri a question out loud – particularly when surrounded by others or in public where your voice could get lost.
Luckily, you can type your questions and requests to Siri without making a sound.
Go to Settings then Accessibility. Choose Siri. On the next screen toggle on Type to Siri.
Now, when you call up Siri it will launch a text input screen instead of the usual audio-powered overlay. Simply type your query and hit Done.