Nearby Mobs Add-on 1.21+

Now you always know who's nearby. Don't forget about those who are always with you—the Creepers, Zombies, and other monsters. The mod Nearby Mobs enhances Minecraft by adding pop-up notifications about mobs around you.

A rather simple addition that makes survival a bit more convenient and better, as the indicator works even through blocks. Below you can see how it works in the game: all the information will be in the bottom right corner.