Siri on your Mac
You can activate Siri with your voice on your iMac and use Siri for many tasks. For example, you can schedule meetings, change preferences, get answers, send messages, place calls, and add items to your calendar. Siri can give you directions (“How do I get home from here?”), provide information (“How high is Mount Whitney?”), perform basic tasks (“Create a new grocery list”), and much more.
Siri is available on your 24-inch iMac or 27-inch iMac whenever you say “Hey Siri” and immediately speak your request, if you enable the “Listen for ‘Hey Siri’” option.
Note: To use Siri, your Mac must be connected to the internet. Siri may not be available in all languages or in all areas, and features may vary by area.
Enable Siri. Open System Preferences, click Siri, and set options. If you enabled Siri during setup, press and hold Command-Space bar to open Siri. Or click Siri in System Preferences, then select Enable Ask Siri. You can also set other options, such as the language and voice to use and whether to show Siri in the menu bar.
Activate Siri with your voice. Press and hold Command-Space bar (or say “Hey Siri” if you have that feature turned on), and start speaking. You can add the Siri icon to the menu bar by selecting that option in the Siri pane of System Preferences. Then click the Siri icon 
to use Siri.
Hey Siri. On your 24-inch iMac or 27-inch iMac, you can simply say “Hey Siri” to get responses to your requests. To enable this feature in the Siri pane of System Preferences, click “Listen for ‘Hey Siri’,” then speak several Siri commands when prompted. On your 24-inch iMac, you can also press and hold the Dictation/Siri (F5) key on your Magic Keyboard with Touch ID.
Tip: To learn about more ways you can use Siri, ask “What can you do” at any time, or see the Apple Support article What can I ask Siri?.
Play some music. Just say “Play some music,” and Siri does the rest. You can even tell Siri, “Play the top song from March 1991.”
Drag and drop. Drag and drop images and locations from the Siri window into an email, text message, or document. You can also copy and paste text.
Change the voice. Click Siri in System Preferences, then choose an option from the Siri Voice menu.
Throughout this guide, you’ll find suggestions for things you can use Siri for—they look like this:
Ask Siri. Say something like:
“Open the Keynote presentation I was working on last night.”
“What time is it in Paris?”
Learn more. See the Apple Support article How to use Siri on your Mac.