Hi...

I'm staying in a rented house(but looking for a new house to buy at the earliest). But recently, I found that the house owner, our neighbour, is examining our house premises when we are out. I suspect that, he would even peek inside the house using the duplicate keys.

So, does anyone know a simple way to detect if the main door is opened, when we are out, before we reach back home ? I don't have much money to buy a security system. So, I'm looking for a simple but efficient way to detect it.

Do you have an idea ?

Thanks in advance...