Headset Notifier is a simple tool that displays a status bar notification when a headset or headphones are plugged into the phone. When supported by the device, it automatically detects if a microphone is available or not.
It can also automatically wake up the screen if the headset is plugged in when the display is turned off. The behavior can be configured in the settings by tapping the notification.
Headset Notifier is available in a free-of-cost version with ads in the settings, or as a paid version without ads.
Headset Notifier is also available as an Open Source project on github.