Acentric and nonpolar Pb2MnO4 was predicted to exhibit unique multipiezo induced magnetoelectric (ME) phenomena. In this paper, we present the results of magnetization as well as dielectric properties as a function of temperature (T), magnetic field (H), pressure (P), and electric field (E) primarily to address the ME coupling and identify the underlying mechanism behind this phenomenon. Magnetization and specific-heat measurements reveal the antiferromagnetic ordering of Mn4+ spins at temperature TN=17K. Metamagnetic transitions at three critical magnetic fields (Hc1, Hc2, and Hc3) are observed for T < TN and H > 3.5 T. Further, the influences of pressure and magnetic field on Hc1 and Hc2 are investigated. The TN, Hc1, and Hc2 all decrease with increasing external pressure. The dielectric anomaly observed at TN is influenced by applying a magnetic field of H > 3.5 T. However, the electric field has minimal influence on the metamagnetic transition. The scaling between dielectric constant and magnetization meaningfully resolves the existence of magnetic-field-induced higher-order ME coupling in Pb2MnO4 at T < TN and H > 3.5 T.