If you are seeking sources of such data, you have to install search coil magnetometers in your filed of study. Once you attain them, you have to look for anomalies if any in order to find any footprint prior or during occurrence of any seismic event. Possibly you may explore possible causes for the enhancements in terms of magnetospheric ULF emissions (micropulsations) and ULF emissions associated with earthquakes using polarization parameter (Z/X) and magnetic storm index Kp variation. Hope it helps.

Sir, So kind of you to hear your answer .sir can I use geomagnetic data which is available online having all the veryical declination etc components to identify ulf precursors??

Interesting question. No fundamental mode has been found yet for this correlation to seismic activity. Here is open field of research, so you can start with monitoring and build your own conclusions about these two phenomena. Regards