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.

For CentOS 8

STEP 1. Enable the EPEL repository

dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

STEP 2. Update the system after the installation of the EPEL repository

dnf update 

STEP 3. Install htop

dnf install htop

For Centos 7

STEP 1. Enable the EPEL repository

sudo yum -y install http://rpms.remirepo.net/enterprise/remi-release-7.rpm

STEP 2. Update the system after the installation of the EPEL repository

sudo yum -y update

STEP 3. Install htop

sudo yum -y install htop