For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security/openSUSE_Tumbleweed/security.repo
zypper refresh
zypper install hashcat
For openSUSE Factory run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security/openSUSE_Factory/security.repo
zypper refresh
zypper install hashcat
For 15.6 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security/15.6/security.repo
zypper refresh
zypper install hashcat
For 15.5 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/security/15.5/security.repo
zypper refresh
zypper install hashcat