If you are using Windows, you need a third-party backup program that supports encryption like EaseUS Todo Backup. For macOS, you can use Time Machine. If you are using Linux, you must use a backup program that supports LUKS encryption. When choosing a backup program, ensure it offers AES 256-bit encryption. This is the most substantial level of encryption currently available. It would help if you also considered using a backup program that offers incremental backup.