Confirmation of marker image recognition and release status for AR image tracking work?,Ar foundation image Tracking

hi!
Help me
I am making an AR game using image tracking technique in unity3d.
After loading the desired 3D modeling object into the marker image, I plan to shoot and kill this object.
I want to give a signal to find the marker image again and recognize it when the distance from the marker image is away or the marker image is out of the camera.
When the image tracking is released away from the marker image, the object floats alone. At this time, I want to turn the object off the screen.
In image tracking, can I receive the signal of the situation where the marker image is recognized and the situation where it is not recognized?