According to Chegg's terms of service,
No materials from the Services may be copied, reproduced, modified, republished, downloaded, uploaded, posted, transmitted, or distributed in any form or by any means without Chegg's prior written permission or as expressly provided in these Terms of Use.
Moreover, according to Chegg, these terms apply "regardless of whether you are a registered user or a guest". It seems to me that this forbids:
a professor to discover answers to their questions on Chegg and alert a grading team to be alert for matching assignments.
a professor to introduce answers downloaded from Chegg as evidence at an academic integrity proceeding.
Does Chegg actually have the ability to forbid these actions?