The Football League's emergency loan window opens on Monday, allowing clubs in the Championship, League One and League Two to strengthen their squads.
Chalobah spent last season on loan at Vicarage Road, making 42 appearances in all competitions and scoring five goals, as Watford reached the Championship play-off final.
They lost to Crystal Palace on that occasion and Chalobah returned to Chelsea, but he has not made a senior appearance for Jose Mourinho's side this season.
Another loan move looks likely and Zola admitted he would be keen on strengthening his squad, with Chalobah set to be his main target.
Zola, who saw a late loan move for Tottenham's Tom Carroll - who went to QPR instead - collapse, said: "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.
"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."