  In this article, using the numerically exact time-evolving matrix product
operators method, we study the fidelity out-of-time-order correlator (FOTOC) in
the unbiased spin-boson model at zero temperature. It is found that after the
initial exponential growth of FOTOC, the information of the system dynamics
will adulterate into the FOTOC. This makes the FOTOC an advanced epitome of the
system dynamics, i.e., the FOTOC shows similar behavior to that of system
dynamics within a shorter time interval. Eventually the progress of the FOTOC
is ahead of the system dynamics, which can provide a prediction of the system
dynamics.
