Learn Turkish: Onu çalışırken çaktırmadan izleyebilir miyim? - Can I watch him secretly while he is working?

Wait, -(y)ken normally refers to the subject of the sentence. How do we know çalışırken means 'while he is working' and not 'while I am working'?

Normally, -(y)ken (while) applies to the subject. However, with verbs of perception or discovery (like izlemek, to watch, or görmek, to see), the -(y)ken verb often modifies the direct object. The accusative pronoun onu (him) is placed right before çalışırken to make it clear that the object is the one doing the working, not you.

What exactly is the word çaktırmadan?

It is a very common, colloquial adverb meaning 'secretly,' 'on the sly,' or 'without letting on.' It is built from the causative verb çaktırmak (to let someone realize/notice) plus the negative adverbial suffix -madan (without doing). Literally, it means 'without letting [him] notice'.

Since he is working right now, why is it çalışırken (aorist) instead of çalışıyorken (continuous)?

Both are correct and mean exactly the same thing here. However, using the aorist tense base (çalışır) before -ken is simply the most traditional and frequent way to say 'while doing' in Turkish, even for actions happening at the present moment.

Could I change the word order and put onu right before the main verb?