If appointments you have entered on your iPhone are not syncing to Outlook on your PC or vice versa, you may need to double-check that you have your Outlook calendar set as the default calendar on your iPhone.
1. Open the Calendar settings
Open the Settings app and scroll down until you see Calendar. Tap to select this.
2. Select Default Calendar
The default calendar option should be towards the bottom of the Calendar settings. Tap this to select it.
3. Choose your Outlook calendar
From the list of calendars, make sure that your Outlook calendar is selected as the default (there will be a tick next to your current default calendar). If another calendar (e.g. iCloud) is selected as default, tap the Outlook calendar to change this to the default.
Once this is changed to your Outlook calendar, try entering a new calendar entry. This should now sync to the calendar in Outlook on your PC.