Thai has no all-purpose yes. ใช่ exists, but it confirms an identification: it answers 'is that your bag?' and not 'did you eat?'. Using it for the second one is understood and slightly odd, in the way that answering 'correct' to 'are you coming?' would be in English.
The general answer to a yes or no question is the verb from the question, said again.
- ไปไหมpaj mǎj
are you going?
- ไปpaj
yes
the verb, echoed. That is the whole answer
- ไม่ไปmâj paj
no
It works for every question type
The pattern does not change with the marker. Whatever verb the question hangs on comes back as the answer, negated or not.
That gives you something genuinely useful in the first months: you can answer before you have parsed the whole sentence, as long as you caught the verb.
- เคยไปไหมkʰɤːj paj mǎj
have you ever been?
- เคยkʰɤːj
yes, I have
- ไม่เคยmâj kʰɤːj
never
And what ครับ is not
ครับ on its own acknowledges that you heard. It is not agreement and it is not yes, though it is constantly used where an English speaker would expect one and it will often pass.
If the answer matters, echo the verb. This also cuts in the other direction: when a Thai speaker answers you with ครับ and nothing else, you have not necessarily been agreed with.