Anyone knows how cricket score API works?

Web sockets. All the data communication happens in real time.

There are vendor who provides data to these apps(or company) like crickbuz, pr any content website for a price. The app can use any technique to update or show real score to users. Maybe WS or refreshing every few seconds.

Not exactly the same question but there are are also handful of Such data providers. Everyone else is a consumer of these data providers. So you can see 100 cricket widgets and pages but in reality only 1-3 data providers would exist. Another fun part to this is that the data the betting apps have has very little lag