how to call function from cli command magento 2

You need to run this command :

php bin/magento cloudways:hicustomer

To call block file you need to do like this :

class Hicustomer extends Command
{
 
    protected $myblockobject;

    public function __construct(\Vendor\Extension\Block\Mycustomblock $myblockobject)
    {
       $this->myblockobject = $myblockobject;
       parent::__construct();
    }

    protected function configure()
    {
        $this->setName('cloudways:hicustomer');
        $this->setDescription('Demo command line');
        parent::configure();
    }

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        
       $myblockobject = $this->myblockobject->create()->MyCustomFunction();

       //call function from block
        $output->writeln("Hi Customer");
    }
}