For a chain, you typically just take your chain wear tool and see if the chain is sufficiently worn, periodically. Cassettes can be done visually (though cog wear tools like the one which is made by Rohloff) exist. These are usually better served by checking cause they're dependent on riding conditions and product types (e.g. 10 speed chains last less long than 7 speed chains) [ A car analogy would be that most manufacturers are now putting in oil life gauges which tell you when to change your oil, rather than just do it on interval, so you maximize the life of your oil. ]
There are also various questions like this one, which you could input the checks into google calendar to get reminders. Things I do by mileage rather than by inspecting the bike on a regular schedule are usually things like repacking my hubs (typically at around 6000 miles in my case), which coincides to be around yearly.