htop is a good option to monitor your system interactively. In order to install htop, you will need to use dnf. If you cannot install htop by yum, you will need to follow following procedure on CentOS 8.
STEP 1. Enable the EPEL repository
dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
for CentOS 7, you should run below
dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
STEP 2. Update the system after the installation of the EPEL repository
dnf update
STEP 3. Install htop
dnf install htop