Running Siri on OS X El Capitan
No, it won't work.

The app will show a prohibitory sign over the app icon.



When opening the App, it will show an error message.



Even if you managed to hack/crack/disable the check that prevents the Siri interface app from running, the parts of the system behind the scenes that actually run Siri on macOS, communicate to the network and process the speech recognition are missing on El Capitan.


  So if the door on the second floor is locked shut because the deck hasn't been built yet - you can cut the lock and eagerly exit the door, but you'll promptly fall to the ground since the deck isn't built into El Capitan yet.