If you look in your System Preferences, look under the help menu, search for Dictation.

There's two panes that give you access to the Dictation settings. One is Accessibility, but the primary pane for Dictation is the Keyboard pane
(Dictation is another way to input text, so Keyboard makes sense.)
Anyway, look at the settings in both Accessibility/Dictation, and Keyboard/Dictation.
And, you do need to have a usable microphone before dictation will function on your mini. The MacBook Pro should work very nicely by just activating Dictation.