Siri on your Mac
You can talk to Siri on your Mac Pro and use your voice for many tasks. For example, you can find files, 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.
Important: Mac Pro doesn’t have a built-in microphone, so you must connect an external microphone (sold separately) in order to use Siri. After attaching your microphone, select it in Sound preferences (click the System Preferences icon 
in the Dock, click Sound, click Input, then select your microphone).
Enable Siri. Click the Siri icon 
in the menu bar, then click Enable when prompted. Or click the System Preferences icon in the Dock, click Siri, then select Enable Ask Siri. You can also set other options, such as Language.
Note: To use Siri, your Mac Pro must be connected to the internet and to a microphone. Siri may not be available in all languages or in all areas, and features may vary by area.
Speak to Siri. Click Siri in the menu bar and start speaking. Or press and hold the Command key and the Space bar, and speak to Siri.
Tip: To learn about more ways you can use Siri, ask “What can you do” at any time, or click the Help button 
.
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.”
Find and open files. Ask Siri to find files and open them right from the Siri window. You can ask by filename or by description. For example, “Show me files Ursula sent,” or “Open the spreadsheet I created last night.”
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.
Pin a result. Save Siri results from Sports, Reminders, Clock, Stocks, Notes, Finder, and general knowledge (Wikipedia, for example) to the Today view in Notifications. Click the plus sign 
in the top right of a Siri result to pin it to the Today View. To see it later, click the Notification Center icon 
, then click Today. If you’re checking a sports score, for example, results stay up to date.
Change the voice. Click the System Preferences icon in the Dock, click Siri, then choose an option from the Siri Voice menu.
Learn more. See the Apple Support article How to use Siri on your Mac.