To turn a smartphone into a home security system, you need a stand and a monitoring app. Set up your smartphone with the stand so that the camera points to the area you want to monitor. Then, install and run a monitoring app on the smartphone. For Andriod phones, the free Salient Eye app sends you an email or text when it detects motion. It also takes pictures of the intruders and uploads them online.
In addition, the Salient Eye app sounds an alarm to scare the intruder, and this alarm requires a password to shut off. If the smartphone has an Internet connection, the app uploads the photos online. You have an option to disable the alarm but keep the photo-taking feature. An optional paid remote control app is available if you want to control your monitoring app remotely.
If you have an iOS device, you can use the free Manything app to monitor your home. This app captures video of an intruder and uploads the video online. The free online storage account can store up to 12 hours of video. This app also supports IFTTT triggers, and you can set up these triggers to perform various tasks, such as updating your social media or turning on an Internet-ready appliance.