Is there a tool to check my exposure from mutual funds towards PAYTM ?

The mutual fund companies sends you monthly portfolio disclosures via email. You can check those.

use phonepay wealth

https://thefundoo.com/Tools/StocksInFund

Check diversification mail...MF houses are heavily invested in Paytm btw

Groww gives option to have a look at individual stocks that are invested via mutual funds for your portfolio at a percentage level