Since there are many blood vessels in both small and larges sizes that are connected with the eyeballs, it is not that easy for the eyes to get out of the eye sockets and fall out, unless some one dig and cut the eyes with something sharp and thin, such as a knife. If so, the eyes can be completely damaged, maybe the person will be blind from then on, or even dead. If the eyeballs fall out, the person should be taken into the hospital as soon as possible, and the doctor will see whether the eyeballscan be restored into the eyes and get those broken blood vessels re-connected with those in the eye sockets. But the successful rate of this surgery is very low.
Dear friend, if your eye falls out, you must pick up your eyeballs immediately and then hurried to a nearby hospital. Usually our eyes will not fall out unless they are damaged by foreign objects such as sharp knives. But if you mean the fake eyeballs, I don't know how to do it because I haven't happen to that occasion before. But I think doctors will fix the fake eyeballs in our eye socket so they won't fall out easily. If they did, you could pick it up and then ask your doctor to put it back to your socket.