Your items in transit can be tracked by visiting the Hongkong Post Mail Tracking page. Please follow the instructions as stated.

 https://www.hongkongpost.hk/en/mail_tracking/index.html

Online tracking information on the delivery status of Registered Airmail / AIR Parcel / EMS Parcel is available only for selective countries. You can connect to the mail tracking website of the country directly. For destinations not on the list, tracking information is only available up to departure from Hong Kong.