If you have a non-magic ability "Magic of meaning", eg. the Chuul, but you're inside a antimagic field, can you detect the magic (from a source that is out of the field)?
The magic meaning trait of chuul states:
Chuul feels magic at less than 120 feet at will. This trait works differently as the detect the magic spell but is not magic itself.
This means that this feature would not be canceled by a antimagic field.
Detect the magic himself has 2 parts, first "to feel the magic" and secondly to see his aura:
During all this time, you feel the presence of magic within 30 feet of you. If you feel magic in this way, you can use your action to see a weak aura around any creature or object visible in the area that is wearing magic, and you'll learn his magic school, if any.
The spell can penetrate most fences, but it is blocked by 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or earth.
Now, antimagic field (the spell) declares that:
This area is separated from the magical energy that permeates the multiverse. In the sphere, spells can not be cast, summoned creatures disappear, and even magic items become mundane.
Spells and other magical effects, except those created by an artifact or deity, are removed from the sphere and can not be protruded.
Will magic auras, which Detect Magic allows you to see, even reach you while you're in the field?
I could not really find a RAW or RAI definition of whether these auras count as a "magic effect," or whether it's essentially a non-magical energy emission that you can not normally see, and that the detection of magic simply expands. you aim the visual range to encompass it.
And the first part, that of feeling the magic in the first place, is left entirely to our imagination, but there must still be some kind of emanation that must reach your player, so the same question arises.