  We report a quasi-periodic pulsation (QPP) event simultaneously detected from
the spatial displacements of coronal loop at both EUV images and microwave
emission during the preflare phase of a C1.1 flare on 2016 March 23. Using the
motion magnification technique, a low-amplitude transverse oscillation with the
growing period is discovered in a diffuse coronal loop in Atmospheric Imaging
Assembly (AIA) image sequences at wavelength of 171 A, and the initial
oscillation period is estimated to be ~397 s with a slow growth rate of 0.045.
At the same time, a QPP with growing periods from roughly 300 s to nearly 500 s
is discovered in the microwave flux in the same active region. Based on the
imaging observations measured at EUV wavelengths by the AIA and at microwave 17
GHz by Nobeyama Radioheliograph, the diffuse coronal loop and the microwave
radiation source are found to be connected through a hot loop seen in AIA
images at wavelength of 94 A. The growing period of the QPP should be related
to the modulation of LRC-circuit oscillating process in a current-carrying
plasma loop. The existence of electric currents may imply the
non-potentialities in the source region during the preflare phase.
