  Entanglement harvesting from the quantum field is a well-known fact that, in
recent times, is being rigorously investigated further in flat and different
curved backgrounds. The usually understood formulation studies the possibility
of two uncorrelated Unruh-DeWitt detectors getting entangled over time due to
the effects of quantum vacuum fluctuations. Our current work presents a
thorough formulation to realize the entanglement harvesting from non-vacuum
background fluctuations. In particular, we further consider single excitation
field states and a pair of inertial detectors, respectively, in $(1+1)$ and
$(1+3)$ dimensions for this investigation. Our main observation asserts that
entanglement harvesting is suppressed compared to the vacuum fluctuations in
this situation. Our other observations confirm a non-zero individual detector
transition probability in this background and vanishing entanglement harvesting
for parallel co-moving detectors. We look into the characteristics of the
harvested entanglement and discuss its dependence on different system
parameters.
