I got these answers from various collegaues. I am mentioning their names and their answers. Hope these would be helpful.
Reetanjali Moharana: It depends on the strength of the black hole, i.e., its mass etc. For typical BH of AGNs have a magnetic field of 10^4 to 10^3 Gauss.
Sibasish Laha :I too am not sure. But as far as I remember it is of the order of micro-Gauss in the disk. Please do have a look at the papers on Magneto hydrodynamical simulations ( by Fukumura et al 2010 ApJ 715.. etc...)
Harold Nations: Popular reference:
https://www.sciencenews.org/...
Pulsar near Milky Way’s center makes first assessment of this type possible.
