Correspondent Daniel Johnson said Evans, 50, observed and assessed engineers and mechanics at work, but not the race drivers Nico Rosberg and Lewis Hamilton.
Mercedes boss Toto Wolff confirmed the news to the German newspaper Bild.
"At Mercedes we want to optimise every aspect of performance, and we believe that there is much to learn from other sports.
"This includes the performance of the whole team and how we act and react in key moments," he added.
The newspaper, revealing that Evans may also attend the Spanish grand prix this weekend, said Wolff received a report from the psychologist after his assessments in Shanghai.