sudo apt-get install hostapd dnsmasq

/etc/dhcpcd.conf

...
#最終行に
denyinterfaces wlan0

/etc/network/interfaces.d/wlan0-static.conf

iface wlan0 inet static
    address 192.168.70.1
    netmask 255.255.255.0
    network 192.168.70.0
    broadcast 192.168.70.255

いったん再起動

zcat /usr/share/doc/hostapd/examples/hostapd.conf.gz > ~/hostapd.conf

sudo cp ~/hostapd.conf /etc/hostapd/hostapd.conf

sudo vi /etc/default/hostapd
DAEMON_CONF="/etc/hostapd/hostapd.conf"

sudo systemctl restart hostapd

/lib/dhcpcd/dhcpcd-hooks/90-dnsmasq

if $if_up; then
  if [ $interface = "wlan0" ]; then
    systemctl restart dnsmasq
  fi
fi