Diagnosis
That's alarming, but it's usually not a ghost. The most common cause is radio interference from a nearby neighbor's opener or device using the same frequency band, accidentally triggering your door.
How to Fix It
You need to change the 'security code' or frequency your iSmartGate uses to talk to your opener. First, go to your garage door opener motor unit and find the 'learn' button. Press it to clear all existing remotes (you'll have to re-pair your car visor buttons later). Then, on the iSmartGate Pro unit itself, there's a row of tiny DIP switches. Change the pattern on these switches—flip a few from up to down to create a new, unique code. Now, press the 'learn' button on your opener again, and within 30 seconds, press the button on the iSmartGate app to send the new code. The opener should blink to confirm.
If That Didn't Work
Check the wiring to your physical wall button. If those wires are frayed or shorting together against metal, they can simulate someone pressing the button. Make sure the wires are secure and not touching each other or any bare metal at the terminals.
Heads Up
After you clear and re-program your opener, you MUST also re-program your car's built-in Homelink system and any other remotes. They were all wiped when you pressed the 'learn' button the first time.