They also have a new device coming in which will let you connect existing wired security sensors to a ring protect system. It hasn’t been released for sale yet, though.
Ring Retrofit Alarm Kit is a Wired-to-wireless bridge that connects to your existing hardwired contact sensors and transmits open/close events wirelessly to Ring Alarm. Connect up to 8 wired contact sensor zones to the device. Set up and configure the device using the Ring app. After installation and setup, monitor and receive notifications when doors and windows with wired sensors connected to Retrofit Alarm Kit open and close. The Ring Alarm Base Station is required to enable Retrofit Alarm Kit features and functions. Once setup, wired sensors connected to Retrofit Alarm Kit can be monitored just like other Ring Alarm sensors in the system.