To answer this question, I want to define “capture the audience” as I think you mean it.

By one interpretation, this could mean how the exposition phase of the narrative hooks the viewer into watching the rest of the film.

By another, this could mean how the aspects of the film as a whole maintain viewer engagement from beginning to end.

I favor the latter interpretation, so I will focus my attention of the acting, cinematography, and editing of the film. First, you might examine how Max Schreck’s unnerving performance as Count Orlock was enigmatic and impactful during its time; viewers actually thought Schreck was a real vampire, for instance. Second, you should explore how F.W. Murnau’s decision to shoot large swathes of on-location, natural settings was revolutionary at the time and contributes to the foreboding atmosphere of the film. Finally, you might look into the use of early practical and special effects, such as the famous coffin-rising shot. These special effects, while not impressive in today’s CGI-laden films, were impressive at the time and still provide that creepy effect Murnau intended.

I hope this helps!