Another one I saw earlier, too late for me as I already have one at full price but I’d recommend Ring (and at this price it’s a steal).
It’s an easy to install video doorbell that records anyone passing or ringing on your doorbell, there’s an intercom so you can interact with them via your mobile phone.
You have to pay £2.50 a month for “video” storage but I’ve found it really useful. It’s great for managing deliveries when you’re away from home and for finding out if someone’s up to no good.
The doorbell can either be wired up to the electrics or like mine run off the battery. I find the battery lasts for about 3 months and takes a few hours to charge. It doesn’t need a professional to install, it’s all easy enough to do yourself.