There are plenty of free DDNS services. Start with your router - a lot of modern routers have this capability. If your router does not support that, check with the CCTV. If everything else fails, you would need to install an update app on a PC.
Check with your ISP as well - they may offer you "static IP address" service. There are ISPs (eg XFinity) where IP address does not change often, if ever.