Dynamical spin-structure factor (DSF) contains fingerprint information of collective excitations in interacting quantum spin systems. In solid state experiments, DSF can be measured through neutron scatterings. However, it is in general challenging to compute the spectral properties accurately via many-body simulations. Currently, quantum simulation and computation constitute a thriving research field, which are believed to provide a very promising platform for simulating quantum many-body systems. In this paper, we establish a link between the many-body dynamics and quantum simulations by studying the nonequilibrium DSF (nDSF) measured on direct product states, which are accessible in contemporary quantum simulators with Rydberg atoms, superconducting qubits, etc. Based on the many-body calculations of transverse field Ising chains, we find the nDSF can be used to sensitively probe the multispinon continua associated with the two-spinon creation and spinon-antispinon process, etc. Moreover, we further demonstrate that the low-energy spinons can be confined—forming spinon bound states—under a finite longitudinal field. Our results pave the way of quantum simulation and manipulation of fractional excitations in highly entangled quantum many-body systems.