The first step is to enable the Microsoft Block on your Moodle site.
Once you click "Add a Block" scroll down until you see "Microsoft Block" and click on it.
Click on "Outlook Calendar Sync Setting"
This will bring up settings that allow you customize how you want the syncing to work and what calendars/Moodle sites you want to sync. Make sure "Enable Outlook Calendar Sync" is checked
Go through and select how you want the sync to behave. For example, if I wanted to have my Sandbox course sync I would check that course and that would bring up some more menu options.
Choose what Outlook Calendar you want to Sync to
Choose Sync Behavior
It may take a while for the sync to occur in the background and refreshing your Outlook Calendar will help force the sync.