The question is self-explanatory: How do I ensure my Mac is not sending data to Apple or programmers?
I seem to recall these options appearing when I last installed the macOS, but want to make sure I did not say yes.
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You can also choose other options from the list on the left (e.g. the Location Services one) to make sure your other privacy settings are okay.
An application-based network filter / firewall such as Little Snitch or Hands Off! is recommended to identify suspicious behavior, though Little Snitch seems trustworthier because they have a legal address; Hands Off! vendor One Periodic on the other hand hide their identity and domain info... guess it's owned by some intel agency...
However, those network monitors might not notify you of connections initiated by services not running under your user name (e.g. those running as root).
There have been efforts to collect phone-home and always-connected behavior by Apple themselves, though I do not have any recent sites at hand other than the apparently obsolete https://fix-macosx.com/ and https://lifehacker.com/lets-talk-about-apples-privacy-issues-1655944758 .
This said, besides that Diagnostic & Usage data mentioned by user242397, there are tons of other services that connect to Apple services.
Right out of my memory:
Oh, and did I mention that Apple collects data about your usage using "differential privacy" beginning with macOS Sierra, which is opt-in according to various news sources (probably via Diagnostics & Usage), but this is anyone's guess and may change over time. In theory, differential privacy ensures that collected data cannot be tracked back to a single user but are cumulated over a group of users, but this only works if there are no flaws in your implementation, and Apple has a track record of being maximally opaque regarding their architectures and designs of such features.