The Hornets failed in a bid to sign Tom Carroll from Tottenham Hotspur on transfer deadline day, and Zola has expressed hope that he can persuade Chalobah to return to Vicarage Road.
"We are still looking for players. We will see if there is anything and we will need to work on that. It is the same as Tom Carroll, we will try and attract the players with what we can offer," Zola told talkSPORT.
"We can't offer what other clubs can offer in terms of money but I think we can attract players. Nathaniel knows what we are and Chelsea know the type of work we do.
"We can still give Nathaniel something to help him develop. So I am relying on this and we'll see what we can do."
Chalobah made 42 appearances for Watford last season.