There are innumerable ways to retrieve information about Bitcoin blocks, including previous block hash. If you're not running your own full node software, you can utilize some external blockchain explorer API to fulfill your needs. Of course, you may also need some additional software to massage the data you get from APIs because not all of them have advanced filtering to extract only the required data. For example, here is a simple script in Python for extracting block hash from specific block height:
thanks for the answer.
my question is, the nonce in header is the start nonce for mining I assume, right? where can I find exact nonce used to solve the target requirement for that block?
also when miner increment nonce, it should be placed in header and header hash recalculatet, right?