Water Alarms or leak detectors: These are small devices that emit a loud sound when they come into contact with water.

Your lender will pull a property profile too so make sure to ask your lender if they found anything unique or alarming in the property profile. 

I think it’s like car alarm: none is 100% proof, but still to have one is much better protection then none.

There are natural disasters every year.If astrology is capable of predicting the future, why didn't these experts sound the alarm in 2007 that the housing crisis was about to hit?

There was one incident where a stolen car entered the neighborhood, and the thief was found sleeping in the car.

(a) Security deposits for residential dwelling units shall be permitted only for the following:(1) The tenant's possible nonpayment of rent and costs for water or sewer services provided pursuant to G.S. 62-110(g) and electric service pursuant to G.S. 62-110(h).(2) Damage to the premises, including damage to or destruction of smoke alarms or carbon monoxide alarms.(3) Damages as the result of the nonfulfillment of the rental period, except where the tenant terminated the rental agreement under G.S. 42-45, G.S. 42-45.1, or because the tenant was forced to leave the property because of the landlord's violation of Article 2A of Chapter 42 of the General Statutes or was constructively evicted by the landlord's violation of G.S. 42-42(a).(4) Any unpaid bills that become a lien against the demised property due to the tenant's occupancy.(5) The costs of re-renting the premises after breach by the tenant, including any reasonable fees or commissions paid by the landlord to a licensed real estate broker to re-rent the premises.(6) The costs of removal and storage of the tenant's property after a summary ejectment proceeding.(7) Court costs.(8) Any fee permitted by G.S. 42-46.Source: North Carolina Tenant Security Deposit Act

One of the first upgrades was battery backup sump pumps with audible alarms.  

Even with all the constables around it would have been a thief's dream, especially if you are assuming some novices had brought thousands in cash.

We will put a portable alarm unit on all our properties so that the appraiser will have to call our agent (my wife) to get into the property.

Implement safety measures: Install safety features like gates with self-closing mechanisms, and pool alarms to minimize the risk of accidents.