A complete understanding of magnetoelectric (ME) coupling in polar magnet Fe 2 Mo 3 O 8 (FMO) remains elusive. Here, we report the magnetodielectric (MD) and ME effects of (Fe 1- x Zn x) 2 Mo 3 O 8 (x = 0, 0.05) single crystals. The observation of MD effect in FMO shows a sharp peak once T is below T N due to the metamagnetic transition, which is converted into an obvious step upon cooling. Meanwhile, the change of magnetization M modulated by electric field E is striking at the dielectric constant peak/step. In (Fe 0.95 Zn 0.05) 2 Mo 3 O 8 , however, the sharp peak at just below T N is intact, while the step at much lower T N is highly damaged. The ME response to 5% Zn2+ dopants at the two T -ranges shows different behavior. Combining with spin wave theory, it is possible to speculate that the inverse Dzyaloshinskii-Moriya interaction might play a dominant role in the ME nature at just below T N , which is different from that at much lower T N. [ABSTRACT FROM AUTHOR]