Liverpool fought back from two goals down to secure the win on Tuesday, with Ngumoha providing two assists for Alexis Mac Allister, who scored twice as the six-time European champions maintained their 100 per cent record in this season's competition.
Villarreal had taken control by racing into a 2-0 lead inside the opening 30 minutes, exposing weaknesses in Liverpool's high-intensity approach. However, Ngumoha's pace, skill and attacking threat helped turn the match around.
The 18-year-old troubled Villarreal's defence throughout the contest, earning praise from Liverpool captain Van Dijk, who believes the winger is only beginning to show his potential.
"He was a complete threat constantly and their defender had a tough time," Van Dijk said.
The Dutch defender also highlighted the benefit Ngumoha gained from training alongside Mohamed Salah before the Egyptian forward left Anfield at the end of last season.
Salah's experience and quality provided the youngster with an opportunity to learn from one of Liverpool's most influential attacking players.
"Everyone is chipping in but for him to work with Mo last year was obviously massive as Mo was one of the best wingers at the club and experienced everything, so why not soak in all the information and show it on the pitch and show your own qualities?" Van Dijk said.
The Liverpool captain was impressed by how Ngumoha has translated that experience into performances this season, but believes the teenager has plenty of room to develop further.
"I think he has shown it this season but there is still much more to come," Van Dijk added.
Liverpool will look to carry their European momentum into the Premier League when they host Brighton at Anfield on Sunday.