Fantastical comes with two extensions for macOS: Share and Quick Look.
Make sure that the Fantastical extensions are enabled by opening System Settings and navigating to the Extensions pane. Select Added Extensions on the left, scroll to "Fantastical" in the list on the right, and check the settings for "Share Menu and "Quick Look."
Quick Look Extension
The Quick Look extension shows event details in spotlight search results.
The Share Extension is available anywhere you see the Share icon in the toolbar. Click the icon and select "Add to Fantastical" from the popup menu.
Fantastical includes a system service, accessible from the contextual menu that appears whenever you right click on selected text. You can use it in almost any app to send text you're reading directly to Fantastical.
Just select the text you want to send, right click (⌃-click) and choose "Add to Fantastical" from the Services listed in the menu. Fantastical will open in your menu bar with the selected text parsed and waiting in the entry field. You can edit it as needed before clicking "Add Event" or pressing Return to create the event.
Apple added new widgets in Notification Center with macOS Big Sur, and Fantastical offers 15 notification center widgets in three different sizes: small (2x2), medium (2x4) and large (4x4).
To add a new widget, open Notification Center, select the option to "Edit Widgets", and select Fantastical from the widget overview or search for "Fantastical". Browse through Fantastical's widgets and click on the widget you want to add to Notification Center.
The following widgets are available to add to Notification Center:
Icon (small): Displays the current month, date, and day of the week.
Date (small): Displays the current month, date, and day of the week.
Date + Calendar (medium): Month, date, and day of the week, plus overview of current month.
Date + Calendar (large): Month, date, and day of the week, plus overview of current month.
Calendar (small): Overview of the current month.
Calendar (medium): Overview of the current and next month.
Up Next (small): Displays the next item in your list, including details.
Up Next (medium): A larger version of the small Up Next widget.
Quick Action (small): A customizable button to perform actions in Fantastical (add events, tasks, or search).
Event List + Date (medium): Month, date, and day of the week, plus an overview of your upcoming items.
Event List (small): Overview of upcoming items.
Event List (medium): Larger version of the Event List widget.
Event List (large): Largest version of the Event List widget.
Event List + Calendar (medium): Overview of current month, plus overview of upcoming items.
Event List + Calendar (large): Overview of current month, plus overview of upcoming items.
To further customize a widget after it has been added to the notification center, right click on the widget and select the "Edit Fantastical" option. The options available here depend on the widget, allowing you to customize the widget's appearance, the quick action button's visibility, active calendar sets, weather, and more.