How are the moves and clock times gathered for events?

Under https://www.chess.com/events, if any event is going on, chess.com will show the live games. How are the moves and clock times determined in real time? Is there an external API to get this information?

They use DGT/Electronic chess boards which give out information about the position, and the clocks also give out their data. I don't know how chess.com gets the data from events they do not host, like the recent world rapid championship (Maybe they make a deal with Fide or something), but I do know that lichess has an endpoint: https://lichess.org/api#tag/Broadcasts/operation/broadcastTourGet

Interesting question and a satisfactory answer to go along with it.

Events that want their games shown provide the URL where they host the DGT links

To add onto Omed's great explanation, I would imagine FIDE give them a websocket they can connect to to pull all the info in real time as it happens. Given the size of chess.com and chess24, I imagine they get access free of charge such they provide the analysis tools.