  We report both 23Na and 75As NMR studies on hole-doped Ca1-xNaxFe2As2
superconducting single crystals (x\approx 0.67) with Tc =32 K. Singlet
superconductivity is suggested by a sharp drop of the Knight shift 75K below
Tc. The spin-lattice relaxation rate 1/T1 does not show the Slichter-Hebel
coherence peak, which suggests an unconventional pairing. The penetration depth
is estimated to be 0.24 {\mu}m at T=2 K. 1/75T1T shows an anisotropic behavior
and a prominent low-temperature upturn, which indicates strong low-energy
antiferromagnetic spin fluctuations and supports a magnetic origin of
superconductivity.
