Little Snitch - Little Snitch is a firewall application that monitors and controls outbound internet traffic.
Micro Snitch - Micro Snitch is an ultra-light menu bar application that operates inconspicuously. It helps figuring out if someone’s spying on you.
NetGuard - NetGuard
Oversight - Get notified when an app accesses your Mac's camera or mic
Portmaster - Is a Privacy Modular Privacy App which includes a "DNS over TLS" feature as well as an "Application Firewall".
AppManager - best Android Apps for tablet and phone