One of the best ways to keep all your contacts and calendars synced in all your devices is by having them stored in a service like G Suite or Office 365.
When having your contacts and calendar in Office 365 or G Suite, you are actually storing your data in the cloud and making it available from any device (PC, Tablet, Phone, etc) with a simple sing into your account. This process also allows you to sync any editing or addition to your data.
If you have a concern about the security of your data, G Suite and Office 365 offer some of the best and more secure cloud services in the market.